Blue Onyx is a variety of Onyx, which is a type of Chalcedony, that crystallizes in the form of blue, white, and brown-banded masses. Just like Blue Chalcedony, its color is caused by what we refer to as the “Tyndall Effect” which occurs when light scatters from colloid-sized particles. The highest-quality Blue Onyx is found in Argentina, while most other commercial deposits are found in Mexico.
